The immediate effects of brain injury in both children and adults are directly related to loss of function in injured regions. In children the effects of early brain injury are further magnified due to distortion of subsequent development, motor learning and skill acquisition. These complications provide a unique opportunity for treatment if changes due to plasticity and distorted learning can be reversed. We have previously shown that children with dystonia due to dyskinetic cerebral palsy (CP) have deficits of sensory processing. Our goal is to show that this deficit specifically interferes with motor learning. The opportunity for improved treatment arises from the potential for improved motor learning if we can increase sensory function or awareness through the use of augmented sensory feedback. We combine a newly-developed figure-8 drawing task from the laboratory of Alessandra Pedrocchi in Milan, with a new speed-accuracy learning paradigm from the laboratory of Pietro Mazzoni in New York to show that deficits of sensory and motor behavior interfere with motor learning. We also test a newly-developed self- feeding task where speed depends upon the ability to carry an object in a spoon. We will determine if model- based interventions can improve real-world function and motor skill many years after injury, using a wearable device that enhances sensory information about muscle activity. We propose the following experiments: 1. Perform a multi-center clinical trial to test the effect of one month of wearable sensory feedback on real-world skill learning in children with dyskinetic CP and primary dystonia. We hypothesize that such intervention will permit acquisition of skills in the child's natural environment that wee not previously achievable through unaided practice, but that these effects will be greatest in children with dyskinetic CP for whom sensory deficits are often present from birth. 2. Test the effect of enhanced sensory feedback during drawing movements and a self-feeding task in children with dyskinetic CP, primary dystonia, and controls. We compare 5 days of learning with augmented feedback to 5 days of learning without feedback. These experiments create a theoretical and experimental foundation for a new understanding of how early brain injury interacts with motor development and skill acquisition in childhood. They perform a multi- center clinical trial of a new noninvasive intervention with significant potential for improving function n this population. They provide a detailed quantification in the laboratory of daily changes due to learning, and the sensory-motor mechanisms responsible for these changes. This understanding will lead to new treatment approaches based on correcting deficits that prevent or distort motor learning. These experiments will provide a significant change in the paradigm for understanding childhood motor deficits, by shifting focus from the immediate effect of injury to the long-term effects on development, motor learning, and skill acquisition.